She must be comparing herself to others at school and believing her worth has to do with her looks or weight. Maybe model healthy eating all together, trail mix, salads, fruits etc. But slowly and maybe she can also go to a therapist herself, or as a family
“She has dreams to be an envy, so she's starving You know, covergirls eat nothing She says beauty is pain and there's beauty in everything What's a little bit of hunger? I could go a little while longer, she fades away”